[TW]Core/MeleeSpellHitResult: Shred & backstab

Fix error in commit 928c37e697b6a516f7d9eb2479503fd188f04885
also just return SPELL_MISS_NONE no need to go through below checks
[TW] Core/Spell: Primal Fury fix idea

- Maybe path to solution seems to work but is somewhat hard to test.
- Bug seems to come from players having both ranks of the talent within
the spell list and then remove or adding rank breaks primal fury(maybe).
Core/Arena: PR/MMR rating change on leave

- Fixes issue if player was last participant in arena match and left
they would avoid rating loss
Merge pull request #32 from gecko32/TWpatch2

[TW]Core/MeleeSpellHitResult: Shred & backstab
Merge pull request #34 from gecko32/ArenaPatch

Core/Arena: PR/MMR rating change on leave
[TW307] - Core/Scripts: Should prevent Raging Spirits from engaging players inside Frostmourne

Thanks to yesitsme for the hint
[TW308] - Core/Scripts: Should prevent Vile Spirits from going inside Frostmourne
[TW309] - Core/Scripts: Some changes to previous commits thanks to gecko32
[TW309] - Core/Scripts: Some more attempts at making Raging Spirits do nothing during Frostmourne phase
[TW311] - Core/Scripts: Stop Vile Spirits at Harvest Soul cast, not after, thanks to gecko32
[TW312] - Core/Scripts: Last push on Raging Spirits
[TW313] - Core/Spells: Some corrections.. nothing important
[TW314] - Core/Scripts: Solve something with paletress
[TW315] - Core/Scripts: Nullify taunts during Bone Storm
[TW316] - Some other trick
[TW317] - I should probably go to bed
[TW318] - Some minor changes
[TW319] - Should prevent Soul Shriek from being cast right as players land at platform
[TW320] - Maybe a better hac.. handling for the previous commit
[TW321] - Increase the delay before Vile Spirits activate on heroic mode after harvest soul